Facile and General Synthesis of Quaternary 3-Aminooxindoles (original) (raw)
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Efficient zinc-mediated allylation, propargylation, and benzylation of isatin-derived imines were undertaken for the synthesis of 3-substituted 3-aminooxindoles with ≈80% yield. Such alternative approach has efficiently avoided the use of catalysts, severe reaction conditions, multistep procedures, and reaction additives. For exploring and materializing the synthetic utility, different allyl, propargyl, and benzyl bromides were used for generalizing the synthetic route. The structure of the synthesized compounds was established and confirmed by 1 H NMR, 13C NMR, FTIR, and mass spectroscopic techniques.
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Tetrahedron Letters, 2006
An unprecedented synthetic approach to novel 4-aryl-1-methyloxindoles is described. The method involves the intramolecular palladium-catalyzed amidation of N-methyl-2,6-dibromophenylacetamide followed by an in situ Suzuki cross-coupling reaction with a (hetero)arylboronic acid in a one-pot reaction.
ChemInform Abstract: Synthesis of Tetracyclic Indoles via Intramolecular α-Arylation of Ketones
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Tetracyclic pyrrolidine/isoxazolidine fused pyrano[3,2-h]quinolines were synthesized via intramolecular 1,3-dipolar cycloaddition in ionic liquid. The transformations are operationally simple and environmentfriendly in nature. The reaction is highly stereoselective affording exclusively the cis fused products, as deduced by the small coupling constant value (J = 4.8 Hz) between ring juncture protons which also showed clear NOESY correlation (in 5a and 5c). Confirmatory evidence came from single-crystal X-ray crystallography of 5d.
Novel β ‐amino Amide Organocatalysts for the Synthesis of Pharmaceutically Relevant Oxindoles
ChemistrySelect, 2019
In this work, a series of novel organocatalysts derived from unique unnatural β-amino acid scaffold were synthesized and further developed to enhance the desired catalytic properties. Their evaluation was carried out in the asymmetric crossedaldol condensation of isatin and enolizable ketone donors. Following a systematic study of the reaction parameters including variations of additive, solvent, temperature, catalyst loading and substrate scope, (1R,2R)-2-amino-N-((R)-1-phenylethyl)cyclohexane carboxamide 9 proved particularly successful, affording the corresponding 3-hydroxy-3-alkyl-2-oxindole in excellent yield (> 99%) and distereoselectivity (> 99% dr) with good enantioselective control (up to 52% ee) in the presence of p-nitrophenol and EtOH in < 24 h. An added benefit of this catalyst was its catalytic activity and selectivity at room temperature eliminating the requirement of reduced reaction temperatures. This scaffold, comprising of β-amino amide, has not yet been applied in organocatalysis, thus, this is the first reported in this growing area. In mechanistic studies, direct infusion ESI-MS proved a valuable tool forproposal of the catalytic cycle, confirming the formation of 2 key reaction intermediates.
Tetrahedron, 2011
The first (organo)catalytic method for regio-and chemoselective aza-FriedeleCrafts (FC) alkylation of indoles and pyrroles with commercially available methyl a-acetamidoacrylates has been discovered. It minimizes/eliminates common competing reactions that occur due to the high and multiatomnucleophilic character of indole and pyrrole. Diverse quaternary a-amino acids were successfully prepared in good yield and high selectivity using low catalyst loading. The enantioselective variant using BINOL-derived phosphoric acids was also explored with indole providing the desired FeC alkylation product with moderate enantioselectivities.
Chinese Journal of Chemistry, 2018
of main observation and conclusion A 4+2 cycloaddition reaction of NH-free benzazetidines with indoles under the catalysis of camphorsulfonic acid was developed. This method shows a broad substrate scope of benzazetidines and indoles, and offers a convenient method for stereoselective synthesis of various cis-2,3-fused indoline aminals. Preliminary mechanistic studies suggest the reaction proceed via a stepwise pathway featuring an electrophilic attack on the benzylic carbon of benzazetidine.
Tetrahedron Letters, 2018
An enantioselective electrophilic amination of 3-substituted-2-oxindoles is reported, using bis(2,2,2-trichloroethyl)azo-dicarboxylate and commercially available Cinchona alkaloid organocatalysts. The best results were obtained in the reaction of 3-aryl substrates, with high to excellent yields (75% to quantitative) and good stereoselectivity (64-77% ee). Facile reductive conversion of the protected 3-hydrazino fragment into the corresponding primary amine was also demonstrated, to expand the synthetic flexibility of asymmetric electrophilic amination with azo-dicarboxylic esters en route to enantioenriched 3-amino-2-oxindoles. The absolute configuration of 3-amino-3-phenyl-2-oxindole was independently established by electronic circular dichroism (ECD), combined with time-dependent density functional theory (TDDFT). .